Ments



(No Model.)

W. H. EASTMAN.

MECHANICAL TELEPHONE.

No. 348,896. Patented Sept. '7, 1886.

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N. PETERS. Phuo-Llthagrnphcr, Washmgnn. D. c.

UNITED STATES PATENT OFFICE.

WILLIAM II. EASTMAN, OF CONCORD,

N. H., ASSIGNOR, BY MESNE ASSIGN- MECHANICAL TELEPHONE.

SPECIFICATION forming part of Lette s Patent No. 348,896, dated September 7, 1886.

Serial No. 153,833. (No model.)

To aZZ whom it may concern.-

Be it known that I, VILLIAM H. EASTMAN, a citizen of the United States, residing at Concord, in the county of Merrimac, and State of New Hampshire, have invented certain new and useful Improvements in Mechanical Telephones, of which the following is a specifica tion.

My invention relates to certain telephones, commonly known as mechanical telephones.

The object of my invention is to avoid too great a ring occasioned by the excessive vibration in center of the diaphragm to lessen the strain on the diaphragm, and to provide means whereby the concave diaphragm may be held in its proper position and at a uniform tension whether in use or not in use.

My invention consists in details of construction, described below, and pointed out in the claims.

In the accompanying drawiugs,forming part of this specification,Figure 1 represents a front elevation of my improved telephone, Fi 2 being a vertical section from front to back. Fig. 3 is a rear view having the center portion of the back board broken out, exposing to view the tensionsprings, Fig. 4- is a vertical section from front to back, shown without the packing, in order to better illustrate the construction.

Similar refercnceletters indicate corresponding parts throughout the various views.

The case consists of the front board, A, hav ing a large central opening, a, for the trans mission of sound, the back board, A, having a small central opening, a, for the passage of a line-wire, and various holes, a", at intervals, near its edge, for the insertion of fasteningscrews for holding the telephone at any desired place,thcse parts being separated by side boards,l3, ol'suitable width to admit the sound ing-boards U U and the supporting-frame D between the front and back board.

To the sounding-board Gisproperly secured a parchment diaphragm, E, and to the sounding-board C, or between it and the board 0, is fastened a wire screen, F, which comes in contact with the diaphragm only at the center, their outer edges being separated, as seen in Figs. 2 and at, and by packing the chamber between the wire screen and the back board, A, with excelsior or a similar material, as seen in Fig. 2, the disagreeable ringing sound,which is so common in this class of telephone, is almost entirely avoided, and from the peculiar position ofthe wire screen F relative to the diaphragm E the packing is allowed to come in contact with the diaphragm only at its center of vibration. The wire screen has, however,

a function aside from the packing-via, it

greatly helps the diaphragm to maintain the line-wire, said screen being in practice very stiff. The line-wire G enters the telephone through the hole a in the back board,A,and is attached in some suitable manner to a short 6 board, A, the former construction being shown in Fig. -11.

Having explained the novel features of my invention, what I claim as new, and desire to secure by Letters Patent, is-- 1. In a mechanical telephone, the construction herein shown, comprising two soundingboards, a wire screen, a suitable packing behind saidscreen, a diaphragm, and suitable springs adapted to maintain a uniform strain on said diaphragm inwardly, all arranged with- '85 in a suitable case, substantially as and for the purpose specified.

2. In a mechanical telephone, the construction herein shown, comprising two sounding boards, a supporting-frame interposed between 0 said sounding-boards and the back board, a wire screen, a packing between said back board and screen, a diaphragm, and suitable springs connecting with the said supportingframe and adapted to maintain a uniform 5 straig on said diaphragm inwardly, all arranged and operating substantially as and for the purpose set forth.

3. In a mechanical telephone, the combina tion, with the conical diaphragm, of a pack IOO ing ofsuitable material arranged behind the means, substantially as described, whereby a former and a wire screen, substantially as uniform tension is maintained upon said diashown, interposed between the packing and phragm independent of the line-wire, all operdiaphragm, and so as to permit the packing ating as and for the purpose set forth. I 5 5 to touch the center or apex of the diaphragm In testimony whereof Iaffix my signature in only, as set forth. presence of two witnesses.

4. In a mechanical telephone, the combina tion, with a diaphragm,of suitableexcelsior or other packing behind the same and a wire XVitnesses: :0 screen interposed between the two and touch- J. B. THURS'ION,

ingsaid diaphragm at its center, as shown, and NATHANIEL E. MARTIN.

VILLTAM H. EASTMAN. 

